Grinding and polishing machine



Dec. 26,1939.

E. GERLACH GRINDING-AND POLISHING MACHINE Filed July 3,. 1937 INVENTOR w .A U an/ fi m N .A M

Patented Dec. 26, 1939 UNITED f STATES PATENT, arms 7 I 2,184,955 A Y GRINDING Am ronrsme Mac Erwin Gerlach, Berlin, Germany, assignor Telefunken Gesellschaftfiir Drahtlose Telegraphic m. b. IL, Berlin, Germany, a corporation of Germany Application July 3, 1937, Serial No. 151,352 In Germany July 10, 1936 3 Claims.

This invention relates to a grinding and polishing machine for bodies soluble in a liquid, preferably of crystalline type, especially such as piezo-electricsalt crystals.

To properly grind the crystals, there is stretched out over a round disk, a cloth which is continuously moistened in the center with the liquid solvent of the crystal body to be ground. For obtaining a uniform distribution of the flowing solvent on the disk, a special distributor for the liquid is provided. At the rotation of the disk, the liquid is being conducted to the edge of the disk owing to the centrifugal force. Since the surface of the disk increases with the distance from the center, the moisture on the grinding surface of the cloth decreases from the center towards the edge. Furthermore, the degree of moisture at the places of the cloth depends on the centrifugal force and also on the number of revolutions and on the supplied quantity of liquid.

Since, as a rule, the body to be ground is held at one place only against the grinding disk, the moisture content of the grinding cloth can, by varying one or several of the aforementioned values, thus be controlled at the place'at which the body is to be ground.

- The provision of the liquid applied to the cloth is to have-a lubricating means between the crystal body to be ground and the cloth so that the body is'prevented from undergoing too great a heating during grinding. Furthermore, the liquid dissolves parts of the body thereby obtain- I ing a smooth surface on the body to be ground.

In order to obtain smooth ground edges of a. body soluble in a liquid, according to a further feature of the invention, care is taken that at the edge past which the grinding disk moves, the liquid iscontinuously passed away. It was found to be of advantage to remove excessive liquid by way of suction. When removing the solvent by means of air suction, the body at the same time may be drawn by the suction against the support whereby it remains fixedly secured thereat.

The drawing shows an example of construction of the grinding and polishing machine according to the invention in schematical representation. a

Figure 1 represents the entire grinding arrangement.

Figures 2a and-2b show the arrangement by which the body to be ground is fixedly held in place. i

In Figure 1, the shaft l of the motor 2 is vertically arranged. The shaft l carries the plate 3 over which is drawn a cloth covering 4 consisting preferably of silk. The cloth is fixedly secured under tension to the plate 3 by means of the ring 5. In the center of the plate 4 there is placed over the cloth covering a layer 6 of blotting'paper on which a holding cap 1 is placed. 1 The diameter of the layer of blotting paper is smaller than that of the grinding disk. The holding cap 'I has in the center thereof a hole 8 through which a tube 9 is inserted serving for the supply of the solvent. The layer 6 of blot- 10 ting paper has the task of distributing uniformly the liquid solvent, so that all places on the cloth covering concentrical with respect'to the drive shaft the same amount of moisture exists.

The crystal body ID to be ground is inserted in a supporting arrangement II. This crystal bodyis held onto the arrangement II by pneumatic action. The arrangement II in turn is fixedly secured to a support not shown in the drawing. The mounting arrangement ll consists of a hollow body whose bottom has preferably a plurality of round openings [2. The air is withdrawn from the hollow body ll through the channel l3 (Figure 1) by means of suction after the body I0 is .fixedly held against the mounting arrangement, so that the said body is fastened to the arrangement .I I. In order that the body to be cut is properly mounted, an abutment bar I4 is provided and which serves forreducing as much as possible'at the cutting performance, the'amount of solvent settling on the body to be cut.

In place of the ordinarily round openings, a suction slot I5 is arranged along the abutment bar [4, the excessive liquid being withdrawn :5 through the said slot by way of suction. The direction of movement of the grinding disk is indicated by the arrow l6.

What is claimed is;

-1. A grinding and polishing machine for piezo- 40 electric bodies soluble in a liquid comprising a rotatable plate driven by a motor, a cap-like liquid distributor located in the center of said plate, the area of said cap-like distributor being small. as compared with the area of said plate, 'means located within said cap comprising a layer of blotting paper for uniformly applying continuous moisture to said rotatable plate, and a support member for said body to be ground located near the outside edge of said rotatable plate.

2. A grinding and polishing machine for piezoelectric bodies soluble in a liquid comprising a rotatable plate having a cloth covering of silk driven by a motor, a cap-like liquid distributor located in the center of said plate, the area of 5 a motor, a cap-like liquid distributor located in.

said cap-like distributor being small as compared with the area of said plate, means located on said cap comprising a layer of blotting paper for uniformly applying continuous moisture to said rotatable plate, and a support member for said body to be ground located near the outside edge of said rotatable plate.

3. A grinding and polishing machine for piezoelectric bodies soluble in a liquid comprising a rotatable plate having a cloth covering driven by the center of said plate, the area of said cap-like distributor being small as compared with the area of said plate, means located on said cap for applying continuous moisture to said rotatable plate, a support member for said body to be ground located near the outside-edge of said rotatable plate, said support member having suction means comprising a plurality of apertures for retaining said body, said support member having a bar and a slot-arranged adjacent said apertures for retaining said body to be ground so that during the cutting performance the in amount of moisture settling on said body is reduced.

' ERwm GERLACH. 

